Tool for sealing a fissure along a mine shaft



United States Patent 3,654,455 TOOL FOR SEALING A FISSURE ALONG A MINE SHAFT Haskell Owen Keltner, Lamar, Colo. (Box 94, Chandler, Okla.) Filed Ang. 31, 1959, Ser. No. 837,013 2 Claims. (Cl. 166-187) This invention is an improvement to that type device which prevents the loss of drilling mud in fissures or cavities encountered along a mining shaft or well bore.

It has been known in the prior art that lost circulation of drilling mud in fractured formations penetrated while drilling a mining or well shaft may be regained by sealing the formation by expanding a deformable member into the fissure by in ating it with a cementitious material.

These fissures or cavities often are bridged by rock ledges or other formations which must be negotlated before the expandable member may be positioned adjacent the area which is to be sealed. Also, cave-ms are a constant hazard around and above these lissures. lt is therefore, a primary objective of this invention to provide protective means which will carry the inliatable member to its proper position and allow a placement operation to continue until the member is positioned at precisely the point desired by the mine operators.

A further objective of this invention is to provide a unique valve means which will allow drilling mud circulation to continue up to the time it is desired to iniiate the expandable member.

A further important objective of this invention is to provide novel means to detach the protective casing after it has carried the expandable member and its associated structure to their proper position and then be withdrawn to a point which will not interfere with the inflating procedure.

Further objectives and advantages of this invention will be apparent from the following description `and claims wherein the construction, arrangement and cooperation of the several parts of the device are set forth.

FIG. l shows the tool at a point adjacent a fissure;

FIG. 2 shows the tool after the fissure has been sealed.

Referring now to the drawings, where like numbers indicate like parts, the numeral designates a mining shaft. As shown, the mining shaft has penetrated a iissure formation 12 which is of such a size, that it is too large to plug with loss circulation materials or cement without the aid of auxiliary equipment.

Disposed adjacent the fissure i2 is the tool 14 which comprises the subject matter of this invention. The tool is lowered through the shaft 10 and main casing 16 via the drill pipe 18. The tool 14 is comprised of a bellshaped cylindrical steel protective casing 2t) within which is an upper plug member 22 `and lower plug member 24 at either end thereof. The upper plug 22 is made of a cement-rubber and liber composition or the like and forms a seal with the upper end of protective casing 29. The plug 22 has a centrally disposed opening 29. The lower or bottom plug 24 also has a centrally disposed opening 26 therethrough. This bottom plug may be made of the same material as upper plug 22.

The openings 29 and 26 are connected by a plastic tube 28. Also joining the upper and lower plugs and surrounding tube 28 is another plastic tube 30 having a plurality of perforations 32 along its length. Attached to plugs 22 and 24 and surrounding the tube 30 coextensive with its length is the plastic deformable and expandable bag 34. The manner in which the above-mentioned tubes and plastic bag are attached to the upper and lower plugs may be by any conventional means such as collars ICC and clamps. The particular fastening means desired will be apparent to those skilled in the art and are not meant to be within the scope of this invention.

The lower plug 24 is generally bowl-shaped and 1s connected to the protective casing 2t) by a plurality of shear pins 36. These pins are made to shear when a pre-determined amount of pressure is exerted agamst them. When the bottom of the shaft is reached, many pounds of drill pipe will be placed on these pins which will shear them, allowing the protective casing to be withdrawn to the vicinity of upper plug 22 as shown 1n FIG. 2.

Referring again to plug 22, it can be seen that the plug is generally circular, having an invested truncated cone section 21 terminating in a circular seat 23 to receive a ball 40 which is slightly larger than the normal size of opening 29. As seen in FIG. l, the plug is spaced slightly from casing 20 except at its upper end. Below the coneshaped section, along the opening 29, are a series of passageways 42 which are in communication with the space 44 between the inner and outer plastic tubes 28 and 3l). Positioned slightly below the openings of passageways 42 and 44 is an annular ball-retaining flange 46.

Prior to the casing 2i) being detached from lower plug 24, it can be seen that a tool which is capable of a drilling operation in itself, is presented to the bottom of the shaft. ln other words, there is no obstruction to mud circulating through tube 28 because the ball 40 will not offer any resistance to material iiowing in that direction. This provides a structure, which is capable of drilling through any bridging formations such as rock ledge or other conditions above the fissure which might (and often does) extend from the fissure formation. In addition, it is normal while using this invention not to drop the ball through drill pipe 18 until it is felt that the tool 14 is properly positioned. However, if after dropping the ball 46 into its proper position a mud-circulating drilling operation can continue due to the valve structure shown.

After the tool has been properly positioned adjacent the fissure 12, the full weight of drill pipe 18 is placed on the protective casing 29, causing shear pins 36 to break. The protective casing is then withdrawn to a point opposite the upper plug 22. The ball 40 is dropped through drill pipe 18 where it will rest over opening 29. A cementitious material 50 is pumped through pipe 18 which will force the upper plug 22 to expand slightly, permitting ball 40 to rest on annular retaining ring 46. This will permit the material 58 to ow through passageways 42 into the space 44 defined between tubes 28 and Si). The material will then ow through the perforations 32 and expand the bag 34 to seal the fissure 12 as shown in FIG. 2. Flap type valves (not shown) can be placed over perforations 32 on the exterior of tube 30 if flowback presents a problem.

The drawings show the shaft drilled to a point slightly below the fissure formation. This shaft is drilled to make sure that the fissure or fracture has all been penetrated, and also to stabilize the bottom of said tool and insure a perfect shut off. The plastic bag, of course, will lap over sufliciently to seal the entire area. The bag may be made of nylon if desired.

The bag 3ft when expanded is approximately 18 in circumference and 6 vertical height, which is of a size adequate to seal a normal fissure encountered during a well-drilling operation. This permits a pillow of cement 6 thick through the fissure area. Of course, this invention is not meant to be limited by the particular Size of the expandable member used.

After the cementing operation has been performed, the drill pipe and steel protective casing may be removed from the shaft. The sealing cement, after it has hardened, and the plastic members remaining in the shaft may l Y e g 3 Y be drilled, by the normal drilling bits available on site in most well-drilling operations.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and etli-f -cient embodiments of .my invention, it should be well understood that I do not wish to be limited thereto, as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as Vcomprehended within the scope of the accompanying claims.

I claim: Y

1. A toolattached to the bottom end of a drill pipe for positioning a deformable memberradjacent a iissure along a mining shaft such that circulation of drilling fluid in the shaft may be restored by inating said member to seal said fissure comprising in combination, upper and lower plug members each having centrally disposed openings therethrough, a rst tube joining said plugs at the peripheries of said openings, a second perforated tube surrounding and spaced from said first tube and joining said plugs, an expansible member surrounding said second tube and connected thereto at points adjacent said plugs, a protective casing surrounding said expansible ,4 Y member, rst means releasably attaching said protective casing to said lower plug until said tool reaches a desired point along said shaft, and second means connected to said protective casing for removing said casing from said surrounding position by releasing said iirstl means, said upper plug' havingow passages communicating the interior of said drill pipe with the space between said rst tube and said perforatedtube, and'thrd means to close the central opening in said upper plug and deect a Vcementitious material owingdownwardly through said drill pipe to the eXpansible member through said ow passages and said perforated tube.

2. The tool described in claim 1 wherein said releasable means are shear pins.

References Cited in thevle of this patent UNITED STATES PATENTS 

